The interoceptive origins of mental imagery: an evolutionary account

Abstract

Contemporary theories suggest that mental imagery evolved to enable prospective simulation of future events for planning and decision-making (Suddendorf and Corballis, 2007; Schacter et al., 2008). Imagery allows organisms to construct hypothetical scenarios, enabling them to test alternative courses of action before acting (Moulton and Kosslyn, 2009). But how did mental imagery emerge from an evolutionary perspective? I propose that imagery's origins lie in interoceptive processing, the phylogenetically ancient system linking internal bodily states to valence, emotion, and motivational salience (Craig, 2009; Barrett, 2017). Interoception is the necessary foundation for any planning system (such as imagery) because planning requires knowing what to plan for; which bodily and emotional states to pursue or avoid. Motor imagery emerged first, by extending forward models offline while inheriting interoceptive integration from survival-relevant actions. However, as social complexity in particular increased, organisms needed to simulate scenarios involving others (e.g., rival alliances, dominance conflicts, mating competitors) and here interoceptive signals alone proved insufficient, since the same autonomic arousal pattern can demand entirely different behavioral responses depending on context. Visual imagery evolved to solve this discriminability problem by binding distinctive sensory features with interoceptive states, creating multimodal representations where affective significance is constitutive of the image itself rather than a subsequent response to neutral sensory content.